How San Diego secured its water supply, at a cost

A hillside is dotted with dried avocado trees after being left fallow, Thursday, May 26, 2022, near Rainbow, Calif. San Diego County's water is among the most expensive in the country. Two rural irrigation districts in the county, home to large avocado industries, want to break away from the regional water supplier, saying they can purchase cheaper water elsewhere. (AP Photo/Gregory Bull)

An official at the Carlsbad Desalination plant fills a cup with filtered water made from ocean water, Thursday, May 26, 2022, in Carlsbad, Calif.The facility is the Western hemisphere's largest desalination plant, which removes salt and impurities from ocean water. (AP Photo/Gregory Bull)

A hillside is dotted with dried avocado trees after being left fallow on May 26 near Rainbow, Calif.

A man performs maintenance work in the reverse osmosis building at the Carlsbad Desalination plant May 26 in Carlsbad, Calif.The facility is the Western hemisphere’s largest desalination plant, which removes salt and impurities from ocean water. (AP Photos/Gregory Bull)

A man performs maintenance work in the reverse osmosis building at the Carlsbad Desalination plant Thursday, May 26, 2022, in Carlsbad, Calif.The facility is the Western hemisphere's largest desalination plant, which removes salt and impurities from ocean water. (AP Photo/Gregory Bull)

As a worsening drought forces millions of Californians to face mandatory water restrictions, one corner of Southern California has largely shielded itself from supply-related woes: San Diego County.